The present invention relates to an electric connector, and more particularly, to an electric connector including locking means for locking the connector and a mating electric connector in an electrical connection therebetween, mounting means for mounting the electric connector onto a mother board such as a printed circuit board, ground straps for grounding the electric connector, and a construction for preventing the electric connector from being improperly fitted to the mating connector.
A conventional electric connector includes an electric insulator, and blocks formed at opposite ends of the insulator. The blocks have insertion holes receiving hexagonal nuts therein. Each of the insertion holes has a hexagonal inner surface in contact with the outer surface of the hexagonal nut and is provided with a pair of ribs on the inner surface which closely fit to diametrically opposite portions of the outer surface of the hexagonal nut.
Another conventional electric connector includes an electric insulator, and blocks formed at opposite ends of the insulator. The blocks have insertion holes in which hexagonal nuts are held. Each of the insertion holes has opposite inner surfaces which face the two axially opposite sides of the hexagonal nut. A plurality of ribs are formed on the opposite inner surfaces and closely fit the nut received in the insertion hole.
In another construction, the inner surface of each insertion hole is provided with a plurality of ribs to closely fit the hexagonal outer surface of the nut.
As for each of the conventional electric connectors, the hexagonal nuts are press-fitted into the insertion holes. As a result, the peripheral surfaces of the nuts or the opposite sides thereof are pinched by the ribs so that the nuts are held in the insertion holes. Bolts are inserted through the tapped holes of the nuts to mount the electric connector on a mother board such as a printed circuit board. Further, bolts are used to conjoin the nuts to other nuts provided in the blocks of a mating electric connector.
However, since it is likely due to the press-fitting of the hexagonal nuts into the insertion holes of the blocks that the ribs are worn or deformed or the blocks are chipped, there is a problem that the nuts are likely to come off out of the insertion holes. There is another problem that if the hexagonal nuts are not completely held in the insertion holes, the nuts are likely to come off out of the holes due to a vibration or the like during the conveyance of the electric connector.
The conventional electric connectors can be plug units or receptacle units, which can be mated or fitted to each other to be electrically coupled to each other. The connector as the plug unit and the connector as the receptacle unit have fitting portions for mating the connectors to each other. The fitting portions are provided with metal covers or metal shells which are for electromagnetically shielding and properly guiding the fitting portions to fit them to each other. Some such metal shells are integrally formed with ground straps for electrically grounding the electric connectors, as described in the U.S. Pat. No. 32,502 granted to Vijay Kumar, Harrisburg, Pa.
Since the fitting portions are symmetrically shaped, there is a problem that the fitting portion of the connector as the plug unit and the fitting portion of the connector as the receptacle unit are likely to be improperly fitted to each other, because they can be fitted to each other as one of the connectors is turned the other way. If the size of each of the connectors is reduced, the thickness of the metal shell is reduced. As a result, asymmetry of the metal shell cannot be made sufficient because the magnitude of the angle thereof and the magnitude of the radius of curvature thereof are limited in the forming process of the metal shell. If such connectors are fitted to each other by a strong force, there is a problem that the metal shells are likely to be deformed to allow the fitting portions to be improperly fitted to each other.
Although the ground straps serve to ground the metal shells, the straps do not function to prevent the hexagonal nuts from coming off out of the insertion holes.